The present invention relates to a buckle device for use in seat belts of motor vehicles, and particularly relates to a buckle device in which impact noises between metal members upon insertion of a tongue plate are reduced and of which structure is simplified. The present invention further relates to a buckle device including a buckle body and a tongue plate, and particularly relates to a buckle device which has an improved structure to prevent detachment of the tongue plate from the buckle body in an emergency of the vehicle, and to a buckle device which is configured to prevent detachment of the tongue plate from the buckle body, when the buckle body is moved in the tightening direction of the webbing by a pretensioner in an emergency of the vehicle.
Conventionally, a seat belt device mounted on a vehicle is provided with a buckle device which comprises a tongue plate movably attached to the intermediate part of a webbing and a buckle body into and from which the tongue plate is inserted and retracted. This buckle device allows the webbing worn by the occupant to be releasably secured to the vehicle body with ease and reliability.
As described in JP, U, 6-66315, a buckle device is comprised of a metal frame, a hook member which is mounted on or supported by the frame pivotably or swingably and which is engageble with and disengageable from a tongue plate, a lock pin made of metal to lock and unlock the pivotal motion of the hook member, a lock pin holder to hold the lock pin, and a biasing member to urge the lock pin via the lock pin holder, an ejector, a spring member to urge the ejector, a release button which is urged by a coil spring in the same direction as that of withdrawal of the tongue plate to disengage the tongue plate, a base cover and lid cover made of plastics, and so forth.
The foregoing frame includes a base plate part and a pair of side plate parts rising from the base plate part, and the pair of side plate parts are formed with a pair of long holes, and a lock pin is passed through the pair of long holes and mounted across the pair of side plate parts. When inserting the tongue plate, the hook member is made to pivot by the tongue plate via the ejector and comes into engagement with tongue plate, and the lock pin is moved to a first position by the urging force of a biasing member to inhibit the pivoting of the hook member to the disengaging side thereby holding the tongue plate and hook member in an engaged state. The foregoing hook member is pivotally urged in the disengaging direction all the time, and when detaching the tongue plate by releasing the engagement between the tongue plate and the hook member, the hook member is made to pivot to the disengage side by switching the lock pin from a first position to a second position by depressing the release button made of plastics, and thus the tongue plate is made detachable.
The buckle device of JP, U, 6-66311 has a basic configuration comprising a buckle body, a hook member which is pivotally supported by the buckle body and is switchable between engaged and disengaged states with respect to the tongue plate, a lock pin which is supported by the buckle body and is movable between a first position to hold the hook member in engaged state, and a second position to disengage the hook member, a release button which is urged toward the withdrawal direction of the tongue plate by a coil spring, and so forth.
Moreover, in the buckle device of this publication, a lock lever is pivotably mounted near the lock pin to cope with a case in which a pretensioner is equipped to retract the buckle body to the tightening direction to tighten the webbing in an emergency of the vehicle. When inserting the tongue plate, the lock pin is moved to and held in the first position by the lock lever which is pivotally urged by a biasing member, and when detaching the tongue plate, the lock lever is forced to pivot to the non-locked position allowing the lock pin to move to the second position.
Furthermore, near the lock lever is provided a plate-like inertial body which is supported and guided to be movable closing to and away from the lock lever and is constantly urged by a spring member in the direction to move away from the lock lever.
When a buckle body comes into an abrupt stop after it is retracted in the tightening direction of the webbing by a pretensioner which operates in an emergency of the vehicle, the inertial body is moved to lock lever side by an inertial force against the urging force of the spring member and is brought into contact with the lock lever thereby preventing the lock lever from pivoting to the non-lock position. Thus arrangement is made to prevent the detachment of tongue plate from the buckle body, which occurs when the lock pin causes the lock lever to pivot to the non-lock position thereby disengaging the hook member.
The buckle device according to JP, A, 4-58963, comprises a latch member which can come into and out of engagement with a tongue plate, an operation member to release the engagement of the latch member, a lock member which moves to a release position in response to operation of an operational member to disengage the latch member, and a lock mechanism which can prevent disengagement of the latch member. An arrangement is made such that the lock mechanism is provided with a motion restriction member which is pivotably mounted on an operation member and partly protrudes into the movable area of the lock member, and when an impact occurs, the moving lock member comes into abutment with the motion restriction member while part of the motion restriction member, which is pivoting, is in the movable area, and thus the movement of the lock member to the release position is arrested.
The buckle device described in JP, U, 6-66315 has a problem in that upon inserting the tongue plate, a sharp impact noise is generated by a collision between the metal lock pin and the metal frame when the lock pin is moved to the first position by the urging force of a biasing member and is received by the ends of the pair of long holes.
Moreover, in this buckle device, since a pin member like a round bar is used as the lock pin, a plastic lock pin holder with a complex structure needs to be provided to hold the lock pin, and thereby the number of parts is increased, the structure becomes more complicated, and also assembly of the buckle device becomes inconvenient.
This buckle device is provided with a coil spring member for urging the release button in the same direction as the detachment direction of the tongue plate in addition to a spring member for urging the ejector in the detachment direction of the tongue plate, and therefore a pair of spring receiving parts to receive the coil spring member as well as the coil spring member need to be provided, and thereby the number of parts is increased, the structure becomes complicated, and also the assembly of the buckle device becomes inconvenient.
Furthermore, in the buckle device described in JP, U, 6-66311, a lock lever and an inertial body are provided so that when the buckle body comes to a sudden stop after being retracted by a pretensioner in an emergency of the vehicle, the inertial body is moved to the lock lever side by an inertial force and is brought into contact with the lock lever thereby inhibiting the lock lever from pivoting to the non-locked position and holding the lock pin in the first position. However, when the buckle body comes to a sudden stop, an inertial force acts on the lock pin as well, and since the lock pin is received directly by the lock lever, a large force is exerted on the lock lever by the lock pin.
Therefore, there is a risk that the lock pin or lock lever or the like may be broken or deformed and thereby the lock pin is moved to the second position thus losing its normal function. To ensure that this will not happen, a lock pin and a lock lever and the like with higher rigidity, therefore of higher cost, need to be used thus leading to a disadvantageous production cost.
Moreover, to prevent the tongue plate from getting detached from the buckle body due to operation of the pretensioner, the lock lever, the inertial body, and urge members to urge these members respectively need to be provided. This would increase the number of parts and make the structure more complex, and assembly of buckle device will become complex thus leading to a disadvantageous production cost. In addition, when inserting the tongue plate, the lock lever pushes the lock pin to the first position and an inclined part of the lock lever, which is pivoting, comes into contact with the lock pin transmitting a force, therefore the insertion operation of the tongue plate may not be smoothly conducted.
Furthermore, in the buckle device described in JP, U, 6-66311, when the inertial body moves to the lock lever side upon a sudden stop of the buckle body, the lock pin may move very fast to the second position since the whole inertial force acting on the lock pin acts to move the lock pin to the second position. That is, since the lock lever may pivot very fast to the non-locked position side, the inertial body, which starts moving upon a sudden stop of the buckle body, may not contact with the lock lever appropriately and thus there is a high possibility that the lock lever is not prevented from pivoting to the non-locked position.
In the buckle device of JP, A, 4-58963, in a normal state, a part of a motion restriction member intervenes into the motion track of a lock member however, since the moving restriction member also pivots due to a collision of the vehicle, the lock member may not abut with the motion restriction member while a part of the motion restriction member stays in the foregoing motion area. If this happens, the latch member will become disengaged thereby causing the tongue plate to be detached.
Therefore the object of the present invention includes: reducing the impact noise between a lock pin and a frame during insertion of a tongue plate, simplifying the structure by eliminating a coil spring member for urging the foregoing release button, simplifying the structure by eliminating the lock pin holder, and so forth.
It is another object of the present invention to provide a buckle device including a tongue plate and a buckle body, in which detachment of the tongue plate from the buckle body in an emergency of the vehicle is reliably prevented, a smooth and secure insertion and detachment operation of the tongue plate is achieved in a normal state, and the structure for preventing the detachment of the tongue plate from the buckle body in an emergency of the vehicle is simplified, and so forth.
It is a further object of the present invention to provide a buckle device including a pretensioner for retracting the buckle body to the tightening side, in which detachment of the tongue plate from the buckle body due to an operation of the pretensioner is reliably prevented, and the structure for preventing detachment of the tongue plate from the buckle body due to an operation of the pretensioner is simplified, and so forth.
Thus, according to the first invention of the present application, there is provided a buckle device, comprised of a tongue plate to be connected to a webbing and a buckle body into and from which the tongue plate is inserted and extracted, wherein the buckle body comprises: a frame; a hook member pivotably mounted on the frame, the hook member adapted to pivot to engage with the tongue plate upon insertion of the tongue plate and urged to pivot to the disengaging direction all the time; a lease button made of plastics and for releasing the engagement between the hook member and the tongue plate; and a lock bar adapted to move to a first position to inhibit the pivoting of the hook member in the disengaging direction by urging force of a biasing member when tongue plate is in engagement with the tongue plate, and to move to a second position to allow the pivoting of the hook member in the disengaging direction by being pressed by the release button during disengaging operation of the release button, and wherein a stop restricting member, adapted to receive the lock bar against the urging force of the biasing member when the lock bar is moved to the first position by the urging force, is integrally formed with the release button.
In the buckle device described above, when inserting the tongue plate into the buckle body, the hook member is made to pivot to engage with the tongue plate along with the insertion of the tongue plate, and the lock bar is switched from the second position to the first position by the urging force of the biasing member thereby inhibiting the pivoting of hook member in the disengaging direction. When detaching the tongue plate, the lock bar is switched from the first position to the second position and the hook member is made to pivot in the disengaging direction to be disengaged from the tongue plate upon disengaging operating the release button, and thus the tongue plate becomes ready to be detached.
On the other hand, when inserting the tongue plate, the stop restriction part, which receives the lock bar against the urging force of the biasing member when the lock bar is moved from the second position to the first position by the urging force, is formed integrally with the release button, and therefore the lock bar is received by the stop restriction part made of plastics when it is switched from the second position to the first position; thus there is no impact noise between a couple of metal members produced and only quieter and milder impact noise than that of metal members is produced.
The buckle device described above may be configured such that: the buckle body comprises an ejector which is pushed by the tongue plate thereby making the hook member pivot in the engaging direction when inserting the tongue plate, and a spring member for urging the ejector toward the disengaging direction of the tongue plate; and when detaching the tongue plate, the ejector is made to abut against the release button and push it in the detaching direction of the tongue plate.
When inserting the tongue plate, pushing the ejector with the tongue plate causes the hook member to pivot in the engaging direction, and thus the tongue plate and the hook member are brought into engagement.
This ejector is urged in the detaching direction of the tongue plate by a spring member and therefore, when the tongue plate is detached, the ejector comes into abutment with the release button by the urging force of the spring member and pushes it in the detaching direction of the tongue plate. In this way, since the release button is pushed in the detaching direction of the tongue plate by exploiting the spring member for urging the ejector, the spring member for pushing the release button in the detaching direction of the tongue plate can be eliminated, and the spring receiving parts to receive the both ends of the spring member can also be eliminated.
Moreover, the buckle device described above may be configured such that: the frame comprises a base plate part, a pair of opposing side plate parts which rise from the base plate part, and a pair of long holes formed in the side plate parts; the above described lock bar is passed through the pair of long holes and mounted across the pair of side plate parts; and the above described stop restriction part is comprised of a pair of receiving parts which receive the both ends of the lock bar projecting outwardly from the pair of side plate parts. In this way, since the lock bar is passed through a pair of long holes and mounted across the pair of side plate parts of the frame, the support of the both ends of the lock bar is stabilized, and thereby the pivoting of the hook member in the disengaging direction is securely inhibited when the lock bar is in the first position. Also since the above described stop restricting part is comprised of a pair of receiving parts which receive the both ends of the lock bar protruding outwardly from the pair of side plate parts, operational stability when receiving the lock bar in the first position is secured.
Furthermore, the foregoing buckle device may include a stopper part which is integrally formed on the frame, and which engages the release button against the urging force of the above described biasing member for urging the above described lock lever.
Upon insertion of the tongue plate, when the lock bar is switched from the second position to the first position by the urging force of the biasing member and is received by the stop restriction part which is integrally formed with the release button, the release button is subjected to an urging force of the lock bar in the detaching direction of the tongue plate, but the release button can be securely kept engaged by the stopper part integrally formed on the frame.
Further, the above described buckle device may be configured such that: the above described lock bar is formed of a strip-type member; the above described release button includes a pair of guide wall parts each of which is closely located outside the above described pair of side plate parts; and the guide wall parts are formed with a pair of guide grooves for guiding the both ends of the lock bar which project from the pair of the side plate parts respectively.
The above described lock bar is formed of a strip-type member, and its both ends are passed through a pair of long holes and guided by a pair of guide grooves, therefore the release button can be movably guided by the both ends of the lock bar via the pair of guide grooves.
A pair of guide wall parts and the guide grooves thereon restrain the lock bar from moving in its longitudinal direction and coming out of the pair of long holes of the frame. The frame, the pair of long holes, and the lock lever restrain the release button from being disengaged from the lock bar and restrict the moving direction of the release button. Thus, the structures relating to the lock bar and the release button are greatly simplified.
Furthermore, the above described buckle device may be configured such that each guide groove is formed of a groove with its both ends closed, and each guide wall part is formed with an import opening part for introducing the end of the lock bar into intermediate part of the length of the guide groove from the direction perpendicular to the guide groove.
Therefore, during the assembly of the buckle device, the release button can readily be assembled by introducing the end of the lock bar into the intermediate part of the length of the guide groove through the import opening part. Moreover, it is possible to minimize the chance that the lock bar comes off the import opening part by forming the import opening part in an appropriate position which does not correspond to the positions of the lock bar when it is in the first or second position.
According to the second invention of the present application, there is provided a buckle device including a tongue plate to be connected to a webbing and a buckle body to and from which the tongue plate is inserted and extracted, wherein the buckle body comprises: a frame; a hook member pivotably mounted on the frame, the hook member adapted to pivot to engage with the tongue plate upon insertion of the tongue plate and urged pivotally in the disengaging direction all the time; a release button for releasing the engagement between the hook member and the tongue plate; and a lock bar adapted to move to a first position, in which the lock bar inhibits pivoting of the hook member in the disengaging direction, by an urging force of a biasing member when being engaged with the tongue plate, and to move to a second position, in which the lock bar allows pivoting of the hook member in the disengagement direction, by being pushed by the release button upon disengaging operation of the release button. The buckle device is further provided with a lock member which is mounted on said frame pivotably between a lock position, in which the lock bar is locked in the first position, and a non-lock position in which the lock bar is not locked; and a biasing member for elastically urging the lock member to the non-lock side, wherein the lock member comprises a base end part pivotally mounted on the frame, a first engaging part formed in its one end, and a second engaging part which faces the first engaging part keeping a space to allow for reception of the lock bar, wherein the first position side end part of the lock bar abuts with the first engaging part maintaining the lock position, and the second engaging part protrudes into the movable area of the lock bar closely facing the lock bar in a state that the lock member rests in the lock position.
When inserting the tongue plate into the buckle body, the hook member is caused to pivot to engage with the tongue plate as the tongue plate is inserted, and the lock bar is switched from the second position to the first position by the urging force of the biasing member, thus inhibiting the pivoting of the hook member in the disengaging direction. The lock member is pivotably mounted on the frame at its base end, and in normal conditions, is elastically urged to the non-lock position by the biasing member. Therefore, when the lock bar moves from the second position to the first position, the lock bar does not interfere with the second engaging part and the first position side end part of the lock bar abuts with the first engaging part thereby causing the lock member to pivot to the lock position. When the lock bar moves to the first position, the lock member settles in the lock position and the lock bar is received between the first and second engaging parts, in which state, the first position side end part of the lock bar abuts the first engaging part thereby maintaining the lock position, and the second engaging part protrudes into the moving area of the lock bar closely facing the lock bar.
On the other hand, when detaching the tongue plate from the buckle body, the lock bar is switched from the first position to the second position upon disengaging operation of the release button; this causes the hook member, which is pivotally urged, to pivot in the disengaging direction to be disengaged from the tongue plate, and thus the tongue plate becomes ready to be detached. When the tongue plate is being inserted, the second engagement part protrudes into the moving area of the lock bar closely facing the lock bar, but when the lock bar starts moving from the first position to the second position, immediately after that moment, the lock bar comes out of abutment from the first engagement part and the lock member, which is urged by the biasing member, and pivots to the non-lock side. Since the switching of the lock bar from the first position to the second position is manually operated and therefore is not very fast, the lock bar moves to the second position without coming into contact with the second engaging part after the lock member has pivoted to the non-lock position.
When the lock bar is subjected to an inertial force in the direction of the first position in an emergency of the vehicle, the lock bar pushes the lock member holding it securely in the locked position with the inertial force in addition to the urging force of the biasing member. On the other hand, when the lock bar is subjected to an inertial force in the direction of the second position, the lock bar starts moving to the second position side.
As described above, in a state that the tongue plate is being inserted in the buckle body, the first position side end part of the lock bar abuts the first engaging part maintaining the lock position, and the second engaging part protrudes into the moving area of the lock bar closely facing the lock bar; therefore the second engaging part receives the lock bar, which has started moving to the second position side, inhibiting the lock bar from moving to the second position. Thus it is made possible to securely prevent the detachment of the tongue plate from the buckle body due to disengagement of the hook member.
The above described function is effective either in a case where an inertial force to the first position is applied to the lock bar due to an impact force in an emergency of the vehicle, or in a case where a pretensioner is equipped so as to retract the buckle body to the tightening side to tighten the webbing in an emergency of the vehicle, and an inertial force to the second position is applied upon operation of the pretensioner, or upon abrupt stop of the buckle body after operation of the pretensioner.
Furthermore, in a normal vehicle collision, the engagement between the hook member and the tongue plate may be released when the hand or elbow of the vehicle occupant accidentally touches the release button of the buckle device due to a sudden change in the posture of the occupant.
However, according to the present application, even if the release button is depressed in the above mentioned situation, the lock member inhibits the movement of the lock bar in the disengaging direction (the second position). That is, since there occurs a delay in the operation of the lock member relative to rapid movement of the lock bar, the lock bar stays in a state in which it inhibits the pivoting of the hook member in the disengaging direction and thus disengagement of the hook member and the tongue plate is prevented.
In the above described buckle device, the base end part of the lock member may be pivoted on the frame at a position spaced away from the plane including the moving area of the lock bar in the direction opposite the hook member.
Thus, the first position side end part of the lock bar, which is moving to the first position, pushes the first engaging part and thereby securely causing the lock member to pivot to the lock position and holding it in the lock position.
In the second invention of the present application, the buckle device may be configured as follows: A buckle device, having a tongue plate to be connected to a webbing and a buckle body to and from which the tongue plate is inserted and extracted, and comprising a pretensioner adapted to retract the buckle body in the tightening direction of the webbing to tighten the webbing in an emergency of the vehicle; wherein the buckle body comprises: a frame; a hook member pivotably mounted on the frame, the hook member adapted to pivot to engage with the tongue plate upon insertion of the tongue plate and being pivotally urged in the disengaging direction all the time; a release button for releasing the engagement between the hook member and the tongue plate; and a lock bar adapted to move to a first position, in which the lock bar inhibits pivoting of the hook member in the disengaging direction, by an urging force of a biasing member when being engaged with the tongue plate, and to move to a second position, in which the lock bar allows pivoting of the hook member in the disengagement direction, by being pushed by the release button upon disengaging operation of the release button. The buckle device is further provided with a lock member mounted on said frame pivotably between a lock position, in which the lock bar is locked in the first position, and a non-lock position in which the lock bar is not locked, and a biasing member for elastically urging the lock member to the non-lock side; wherein the lock member includes a first engaging part with which the first position side end part of the lock bar can abut and a second engaging part which protrudes into the movable area of the lock bar and with which the second position side end part of the lock bar can abut; and wherein the lock bar, which is urged to the first position, abuts the first engaging part causing the lock member to pivot to the lock position, and the lock bar, which has started moving toward the second position due to an inertial force generated upon a sudden stop of the buckle body after an operation of the pretensioner, is received by the second engaging part, thus the movement of the lock bar to the second position is inhibited either when the pretensioner is in operation or when not in operation.
During a normal state in which the pretensioner is not in operation, in a situation where the tongue plate is being inserted in the buckle body, the first position side end part of the lock bar abuts the first engaging part causing the lock member to pivot to and to be held in the lock position. In this state, the second engaging part protrudes into the movable area of the lock bar, and upon operation of the pretensioner in an emergency of the vehicle, the buckle body is retracted in the webbing tightening direction and then comes into an abrupt stop generating, firstly, an inertial force which acts on the lock bar in the direction to the first position immediately after the buckle body has started moving. At this time, the lock bar pushes the lock member with the inertial force in addition to the urging force thereby maintaining the lock member securely in the lock position.
On the other hand, upon an abrupt stop of the buckle body, the lock bar starts moving toward the second position side under an inertial force.
In a state in which the tongue plate is being inserted in the buckle body, as described above, since the lock member is held in the lock position and the second engaging part protrudes into the movable area of the lock bar, the second engaging part receives the lock bar which has started moving toward the second position inhibiting the movement of the lock bar to the second position, and thus it is possible to securely inhibit the detachment of the tongue plate from the buckle body. Other functions except the one in an emergency of the vehicle are generally the same as described before.
The buckle device according to the second invention may be configured such that the above described lock member is pivotably mounted on the frame via a pivot part which is off-centered from the center of gravity of the lock member so that an inertial force acts on the lock member causing it to pivot to the lock position side upon a sudden stop of the buckle body after operation of the pretensioner.
That is, upon a sudden stop of the buckle body, since the lock member is securely held in the lock position, it is made possible to securely receive the lock bar, which has started moving toward the second position, with the second engaging part.
At this time, the weights of the lock member and lock bar, urging force of the biasing member, and the pivot position of the lock member may be determined so that the lock member can be suppressed by the lock bar and held in the lock position upon a sudden stop of the buckle body after an operation of the pretensioner.
Furthermore, the buckle device according to the second invention may be configured such that the second engaging part of the lock member exerts a pivoting force on the lock member to pivot to the lock position side upon coming into contact with the lock bar which is moving to the second position side.
Therefore, even when the second engaging part of the lock member has not fully intervened into the movable area of the lock bar, it is possible to make the lock member pivot to the lock position when the lock bar, which started moving to the second position side, comes into contact with the second engaging part. Thus, it is made possible to make the second engaging part fully intervene into the movable area of the lock bar, and thereby have the lock bar securely received by the second engaging part.
Next, according to the third invention of the present application, there is provided a buckle device; including a tongue plate to be connected to a webbing and a buckle body into and from which the tongue plate is inserted and extracted, and equipped with a pretensioner adapted to retract the buckle body in the tightening direction to tighten the webbing in an emergency of the vehicle; wherein the buckle body comprises: a frame; a hook member pivotably mounted on the frame and adapted to pivot to engage with the tongue plate upon insertion of the tongue plate and being pivotally urged in the disengaging direction all the time; a release button to release the engagement between the hook member and the tongue plate; a lock bar adapted to move to the first position to inhibit the pivoting of the hook member in the disengaging direction by an urging force of an biasing member, and to move to the second position to allow pivoting of the hook member in the disengaging direction by being pushed by the release button upon disengaging operation of the release button. The buckle device is further provided with a lock lever which is pivotable between a lock position to lock the hook member, which is in engagement with the tongue plate, to be unable to be disengaged and a non-lock position to allow disengagement, and which is urged to the non-lock position all the time, wherein the lock lever is pivotably mounted on the frame via a pivot part which is off-centered from the center of gravity of the lock lever, and upon operation of the pretensioner, the lock lever pivots to the lock position urged by an inertial force just after the buckle body has started moving, and the lock bar moves to the second position urged by an inertial force when the buckle body abruptly stops, thus the pivoting of the lock lever from the lock position to the non-lock position is inhibited.
When inserting the tongue plate into the buckle body, the hook member pivots and come into engagement with tongue plate as the tongue plate is inserted, and then the lock bar is moved from the second position to the first position by the urging force of the biasing member and inhibits the pivoting of the hook member in the disengaging direction. When detaching the tongue plate, upon disengaging operation of the release button, the lock bar is moved from the first position to the second position and thereby the hook member, which is pivotally urged, pivots in the disengaging direction to disengaging the tongue plate, thus the tongue plate becomes ready to be detached.
In a normal state in which the pretensioner is not in operation, the lock lever is urged to the non-lock position all the time. In an emergency of the vehicle, the pretensioner operates and the buckle body is retracted in the tightening direction of the webbing and then stops abruptly. At this time, first the lock lever pivots to the lock position urged by an inertial force immediately after the buckle body has started moving, then the lock bar moves to the second position urged by an inertial force when the buck abruptly stops, and thus the lock bar inhibits the pivoting of the lock lever from the lock position to the non-lock position. After operation of the pretensioner, the lock bar returns to the first position urged by the biasing member, and thereby the lock lever is urged to pivot to the non-lock position returning to a normal state.
Thus, if the lock lever is not provided, the lock bar undergoes an inertial force thereby moving from the first position to the second position, and the hook member is disengaged and thus the tongue plate may be detached from the buckle body. But with a lock lever being provided, even if the lock bar moves to the second position, the lock bar inhibits the pivoting of the lock lever from the lock position to the non-lock position, thus it is made possible to securely prevent the detachment of the tongue plate from the buckle body.
Moreover, detachment of the tongue plate from the buckle body due to operation of the pretensioner can be prevented by a simple structure comprised of a lock lever and so forth, thereby resulting in an advantageous production cost. Furthermore, when the lock bar is moved to the second position by an inertial force upon an abrupt stop of the buckle body, the lock bar is received resiliently by a biasing member thereby allowing normal operation without being broken or deformed.
The above described buckle device may be configured such that the lock lever is provided with a contact part at its tip part so that the lock bar, which has moved to the second position upon an abrupt stop of the buckle body, comes into contact with the contact part thereby holding the lock lever in the lock position. That is, the lock bar, which has moved to the second position, comes into contact with the contact part of the lock lever upon abrupt stop of the buckle body thereby holding the lock lever in the lock position, and thus it is made possible to securely inhibit the pivoting of the lock lever to the non-lock position.
In the above described buckle device, the lock lever may have an inclined guiding part which undergoes a pivoting force toward the lock position exerted by the lock bar which is moving to the second position.
That is, when the lock lever is about to move from the lock position to the non-lock position, the lock, bar which is moving to the second position, comes into contact with the inclined guiding part of the lock lever thereby urging the lock lever to pivot to the lock position side, and thus it is made possible to have the lock lever forcibly pivot to and held in the lock position.
In the above described buckle device, the center of gravity of the lock lever is preferably disposed such that the lock lever is pivoted toward the lock position by the inertial force which acts on the center of gravity of the lock lever upon movement of the buckle body.
That is, it is possible to have the lock lever securely pivoted to the lock position by an inertial force which acts on the lock lever just after the buckle body has started moving.
Furthermore, the above described buckle device may be configured such that, the lock lever comprises a first and second levers which are pivotable about a common axis, wherein the first lever pivots urged by an inertial force just after the buckle body has started moving, and the second lever is pushed by the first lever to pivot to the lock position, and the second lever is held in the lock position side by an inertial force when the buckle body comes into an abrupt stop.
In this buckle device, the second lever is pushed to pivot to the lock position by the first lever which is pivoted by an inertial force just after the buckle body has started moving, and then the second lever is held in the lock position side by an inertial force when the buckle body comes into an abrupt stop. That is, when the buckle body stops abruptly, the lock bar moves to the second position thereby restraining the second lever from pivoting from the lock position to the non-lock position more securely, and thus it is possible to securely prevent the detachment of the tongue plate from the buckle body.